Encryption techniques typically provide for a “session key” for encrypting data sent across a communication link. Data sent across a communication link is typically either unicast communication, broadcast communication, or multicast communication. A unicast communication is data sent from a sending host to a receiving host. Broadcast communication is data sent from a sending host to all other hosts on a specified network. Multicast communication is data sent from a sending host to a defined group of receiving hosts.
A unique session key generated on one side of a remote communication link could be used to encrypt broadcast data and send it across the communication link, but because broadcast data is sent to more than one party, the session key would have to be defined and distributed to all parties who would receive the broadcast data. A static approach wherein the session key is well defined and distributed across the communication link would be susceptible to attack and therefore might not be secure.
Additionally, multicast sessions are similar to broadcast sessions in that data is distributed to more than one host. Multicast sessions therefore suffer from the same problem as described above, where a static key distributed to all multicast receivers would be susceptible to attack. Also, multicast sessions tend to be ad-hoc, and distributing static keys for multiple multicast sessions would require considerable planning and management.